The bond traders at Cantor Fitzgerald, LP, were proud of their innovations, of their influence in moving billions of dollars in U.S. Treasury securities each year and of their perch atop the gleaming, 110-story World Trade Center.

In the north tower, where the firm had offices between the 101st and 105th floors, only the restaurant Windows on the World stood higher. The company's late founder, Bernard Cantor, for years boasted of having the world's highest museum, exhibiting some of his collection of Rodin sculptures outside his 105th-floor office, including a copy of "The Thinker."

The setting, said Mike McManus, who worked at Cantor for 10 years, "was magnificent ... There were days when the cloud cover was actually below you. There would be an overcast day in New York, but working at Cantor ... [you] had sun streaming through the windows. It was like you were on top of the world."

But in less than an hour Tuesday, Cantor's lofty headquarters operation perished. And absent a miracle in the search for survivors, so did about 700 company employees - one of the most staggering losses to a single firm from the terrorist attack that imploded both towers and killed thousands.

About 300 headquarters employees survived because they were absent by chance. Christopher Pepe, an employee of Cantor's eSpeed division, left the building minutes before the impact to go to Starbucks because he did not want to drink the office's "garbage coffee," McManus said. And chief executive officer Howard Lutnick got to work late because he had taken his son to his first day of kindergarten.

Each day since the attack, employees, friends and family members have gathered at the Pierre Hotel off Central Park to console each other, some clinging to hope, others beginning to grieve. In a closely guarded meeting area, they have mounted pictures of the missing employees on a wall in a giant collage, had sessions with counselors and cried together.

On Friday, Richard Murach was in tears as he stood outside the hotel and contemplated the loss of his 45-year-old brother, Robert - a husband, father of two young children and the senior vice president of Cantor's prestigious treasury department.

"He was a great guy. He turned lemons into lemonade ... so talented and humble, a brilliant guy," he said. "But his death is no bigger than [that of] the hot-dog vendor on the ground. Everybody's death is important."

He said family members are "looking for closure ... When we feel that we're over it, we start crying again and it makes you feel better. And then there's some hope, and you hold hands and you hug and you talk about it. And then you feel worse. It's a roller coaster that's going to go on for the rest of our lives."

Not since 8:50 a.m. Tuesday, two minutes after terrorists slammed a hijacked jetliner into the north tower 15 floors below, has anyone heard from the traders, executives and support personnel who were in Cantor's offices. With smoke pouring in from below, numerous Cantor employees spent those two minutes frantically phoning family members to say goodbye and "I love you," said McManus and other friends.

Fran LaForte, who is eight months pregnant, told friends that she dropped her kids off at school and returned to her suburban New Jersey home Tuesday morning to a taped farewell message from her husband, Michael. Lutnick told ABC News that his brother, Gary, made a similar call to their sister.

"He was stuck in a corner office," Lutnick said, describing his brother's message. "There was no way out. And the smoke was coming in and it is - it's not good, and ... he's not going to make it. And he just wanted to say that he loved her and wanted to say goodbye ... And then the phone went - the phone went dead," he said.

Lutnick said he arrived to find the building on fire and stood at the bottom, frantically questioning fleeing occupants as to what floor they had come from. The highest he heard was the 91st. Lutnick said that when the second plane hit, people began screaming and he turned and ran, but was knocked to the ground amid smoke and debris. After the buildings collapsed, he told ABC, he "just walked north" for hours.

Richard Murach said he has since learned that his brother was on the phone with his counterpart in London when the plane hit. "He knew something had happened. Then the phones went dead."

"We don't know ... if it went quick, if it was a fireball, if they had time to pray," he said. But even if the stairwell wasn't cut off by the crash, he said, "My brother, the type of guy he was, he would have hung around and helped somebody who needed help getting out."

McManus and another former employee, though, said Cantor's employees had little chance of survival even if the stairwell was accessible, given that the building collapsed within an hour.

When a terrorist bomb went off in the building's basement in 1993, McManus said, the stairs were so crowded that it took him two hours and five minutes to get down 105 floors. "It was a step at a time," he said.

Gary Ekelund, a former Cantor employee who works with McManus at a competing firm, said it took him 3 1/2 hours to get out in 1993. "The building [was] a death trap. Always has been," he said.

Ekelund, ironically, may owe his life to Cantor's innovation. When the firm shifted from voice trading to electronic trading in recent years, it reduced its Treasury securities trading staff from 500 to 40. Ekelund was among those laid off.

Cantor Fitzgerald, which had backup systems at offices in London and New Jersey, managed to resume trading Thursday and Lutnick vowed that "we will not allow this tragedy to sway us from our path. While we grieve, we intend to persevere."

But he also declared in TV interviews that he now has 700 families to take care of, and he initiated a donation program for the victims' families with a $1 million personal contribution.